1. Field of the Invention
The present invention relates to an optical switching connector used for switching optical paths in an optical fiber line.
2. Description of the Related Art
As one of prior art optical switching connectors used for switching optical paths of optical fiber lines, there has been known the one as shown in FIG. 1a and 1b, disclosed in Japanese Unexamined (Kokai) Patent Application Publication No. 63-85522.
This optical switching connector has a first ferrule 11 and a second ferrule 12 arranged with end faces abutting each other. The first ferrule 11 has two parallel pin holes 13a and 13b, while the second ferrule 12 has two parallel pin holes 14a and 14b. In the corresponding pin holes 13a and 14b and 13b and 14a are inserted reference pins 15 for positioning purposes in a manner so as to span the two ferrules 11 and 12. The respective ones of the pin holes of each of the first and second ferrules 11 and 12, that is, 13a and 14a, are formed to a size which will prevent horizontal movement of the reference pins 15, while the other pin holes 13b and 14b are formed with horizontally longer sectional shapes so as to allow the reference pins 15 to move horizontally by a predetermined pitch P.
Between the two pin holes 13a and 13b of the first ferrule 11n are fixed four optical fibers 17a to 17d of a four-core tape-core line 16 with their end faces exposed, while between the two pin holes of the second ferrule 12 are fixed the two optical fibers 19a and 19b of a two-core line, for example.
If the first ferrule 11 is fixed and the second ferrule 12 is made to be movable horizontally (the reverse is also possible), then in the condition with a force in the direction of the arrow A applied to the second ferrule 12 as shown in FIG. 1a, the two optical fibers 19a and 19b of the second ferrule 12 are connected with the two optical fibers 17a and 17b on one side of the first ferrule 12 to form optical paths. Thereafter, if force in the direction of the arrow B is applied to the second ferrule 12 as shown in FIG. 1b, this moves horizontally and the optical fibers 17c and 17d on the other side of the first ferrule 11 to form optical paths.
The optical switching connector performs switching of optical paths in the above manner.
The above-mentioned first and second ferrules are required to have high dimensional precision, and thus are comprised as the optical switching connector shown in FIG. 2. That is, the optical switching connector 21 is comprised of a ferrule plate 22, a pin holding member 23, a frame body 24, and screws 25a and 25b.
The ferrule plate 22 fixes the end portion of the optical fiber 17 to predetermined position, has pin grooves 26a and 26b formed in parallel at its both sides, has one of the pin grooves 26a formed to a width preventing horizontal movement of the reference pin 15, and has the other pin grooves 26b formed to a width enabling horizontal movement of the reference pin 15. The pin holding member 23 serves as a cover for positioning the reference pins 15 in the pin grooves 26a and 26b, so the pin holes are formed by the pin holding member 23 and the pin grooves 26a and 26b. The ferrule plate 22 and the pin holding member 23 are housed in the frame body 24 and screws 25a and 25b are used to fasten them to form a single body.
Note that the pin grooves 26a and 26b sometimes are both formed to widths enabling the reference pins 15 to move horizontally by a predetermined pitch. In this case, the pin grooves of the opposing optical switching connector are both formed to widths preventing horizontal movement.
This type of conventional optical switching connector has the pin holding member 23 formed of a single plate which is fastened by screws 25a and 25b from directly above the pin grooves 26a and 26b. As a result, bending of the pin holding member 23 occurs at the wide width pin groove 26b as shown by the dotted line A and there are cases where the reference pin 15 cannot be inserted and cases where even when insertable, the resistance to horizontal movement is great and the switching operation cannot be performed smoothly.
Since the pin holding member 23 is a single plate, in the case where the diameter of the reference pin 15 is larger than the design value or the case where the width of the pin groove 26a is smaller than the design value, as shown in FIG. 3, the pin holding member 23 becomes slanted, the switching direction and the direction of arrangement of the optical fibers deviate from each other, and the connection loss increases.
Further, as shown in FIG. 4, in the case where the diameter of the reference pin 15 is smaller than the design value or the case where the width of the pin groove 26a is larger than the design value, the position of the reference pin 15 is uncertain, as a result, the connection loss also increases.